An endoscope device has been conventionally known which acquires a normal light image such as a white light image and a narrow-band light image such as a fluorescence image, and superimposedly displays the normal light image and the narrow-band light image (for example, see PTL 1). In a method for superimposing the normal light image and the narrow-band light image in PTL 1, the narrow-band light image is added to one of three-color component images of R, G, B constituting the normal light image.